Current operative methods for treating spinal deformities, particularly scoliosis, include correction of the curve by some internal fixation device, and fusion of the spine in the corrected state usually accomplished by the placement of bone graft between vertebrae. This is usually accomplished with posterior surgery, although anterior procedures are becoming more popular, as well as combinations of anterior and posterior procedures. Several instrumentation systems are available from various manufacturers to correct and stabilize the spine while fusion occurs. Among them are TSRH(copyright), CD(trademark), CD Hopf(trademark), CD Horizon(trademark), ISOLA(trademark), Moss Miami and Synthes Universal Spine Systems. Nonoperative methods do exist and are used when applicable. These nonoperative methods include bracing and observation.
Juvenile idiopathic scoliosis occurs between the ages of 4 and 10 years. It can resolve spontaneously, respond to nonoperative therapy, or progress until fusion is required. Stapling across long bone physes has long been recognized as a predictable method of treating limb malalignment. Vertebral interbody stapling across the cartilaginous endplates and discs was attempted by Nachlas and Borden in a canine scoliosis model. Early human results in the 1950s were disappointing. Roaf reported limited successful correction of scoliosis by uninstrumented convex hemiepiphysiodesis. His study did not have a uniform patient population by skeletal maturity or scoliosis etiology.
Further shortcomings of current operative methods and devices are numerous. Patients with juvenile scoliosis who undergo curve stabilization with subcutaneous rods would be subject to multiple surgical procedures for lengthening as they grow. Anterior and/or posterior spinal fusion in the skeletally immature patient often results in loss of vertebral body height and girth. Additionally, poor self-image may occur in adolescent patients who are braced for scoliosis. Moreover, curve stabilization with bracing is only successful in approximately 75% of patients. Another problem is that some children, while not currently candidates for a definitive fusion procedure, are likely to need such a procedure in the future. These would include children less than ten years of age, small in stature, premenstrual or riser two or lower, and those not physically able to tolerate the surgery required for a definitive fusion procedure. It would be preferable to eliminate the need for that procedure altogether.
Described briefly, one embodiment of the invention is a fusionless method of treating abnormal alignment of a spine of a child or a young adult. The spine has a convex side and a concave side. The method comprises the steps of attaching a tether to at least two vertebral bodies of the spine and then constraining curve progression in a portion of the convex side of the spine.
Another embodiment of the invention is a fusionless method of correcting deformities in a spine of a child or a young adult. The spine has a convex side and a concave side. The method comprises the steps of attaching a tether to at least two vertebral bodies of the spine and selectively constraining growth of the convex side of the spine.
Another embodiment of the invention is a device for restraining growth in a spine having a convex side and a concave side. The device comprises a strand, at least two blocks and a plurality of fasteners. Each block has a top surface, bottom surface and a first and second set of opposing side surfaces. The block is oriented on the spine so that the first set of side surfaces are located on an anterior part and a posterior part respectively of the spine. The block has a generally curved shape in a transverse direction from the anterior part to the posterior part corresponding to the antero-lateral anatomy of vertebral bodies. The bottom surface of the block is configured to contact a vertebral body. At least one fastener connects each block to at least one vertebra on the convex side of the spine. Each block has at least one channel for receiving the strand. Each block also has at least one bore extending between the top and bottom surfaces of the block. The bore receives one of the fasteners which connect the block to a vertebral body.